Rotor flap high lift system



Aug. 31, 1965 P. F. GIRARD 3,203,649

ROTOR FLAP HIGH LIFT SYSTEM Filed Dec. 23, 1965 5 Sheets-Sheet 1 INVENTOR. PETER F. GIRARD E BY madam:

Aug. 31, 1965 P. F. GIRARD ROTOR FLAP HIGH LIFT SYSTEM 3 Sheets-Sheet 2 INVENTOR. PETER F. GIRARD Aug. 31, 1965 P. F. GIRARD 3,203,649

ROTOR FLAP HIGH LIFT SYSTEM Filed Dec. 23, 1963 3 Sheets-Sheet 3 if mi i H INVENTOR.

PETER F. GIRARD United States Patent 3,203,649 ROTOR HIGH LIFT SYSTEM Peter F. 'Girard, La Mesa, 'Calif., assignor to The Ryan Aeronautical (30., San Diego, Calif. Filed Dec. 23, 1963, 'Ser. No. 332,767 6 Claims. (Cl. 244-'42) The present invention relates to aircraft and more specifically to a rotor flap high lift system.

Aircraft designed for STOL (short take-01f and landing) performance have utilized a number of ways to augment or increase lift. These include direct lift from auxiliary rotors or fans, or movable primary propulsion ro tors or fans, which may even provide sufficient power for direct vertical take-off. Large trailing edge flaps have also been used, with various blowing and suction means to direct the airflow, also boundary layer control systems with means to ensure that the airflow remains attached to the wing surfaces for maximum efficiency. The present system combines features and advantages of several of these systems, yet remains basically simple in structure and operation.

The primary object of this invention is to provide a high lift system incorporating a plurality of small, individually powered rotors mounted above the trailing edge of a wing to provide a downward airflow and create an aerodynamic sink at the trailing edge in the manner of a large high lift flap.

Another object of this invention is to provide a high lift system wherein the downward airflow from the rotors adds direct lift to that of the wing and also causes the airflow to remain attached to the upper surface of the wing, so that breakaway and stalling are prevented.

Another object of this invention is to provide a high lift system wherein the rotors are retractable into the wing when not in use, the mechanism including indexing means which automatically aligns the rotor blades for storage in compartments of minimum size.

A further object of this invention is to provide a high lift system wherein the rotors can be powered at all times when in use, or may be allowed to auto-rotate when maximum effect is not required, as during an extended climb with a heavy load after initial speed has been built up, or during descent prior to landing.

In the drawings:

FIGURE 1 is a partial top plan view of an aircraft illustrating the rotor installation;

FIGURE 2 is a sectional view taken on line 2-2 of FIGURE 1;

FIGURE 3 is an enlarged sectional view taken on line 33 of FIGURE 1;

FIGURE 4 is a sectional view taken on line 44 of FIGURE 3;

FIGURE 5 is a sectional view similar to FIGURE 3, but with the rotor extended;

FIGURE 6 is a top plan view of one rotor in retracted position, the doors being partially cut away;

FIGURE 7 is an enlarged side elevation view of a rotor head;

FIGURE 8 is a sectional view taken on line 8-8 of FIGURE 7;

FIGURE 9 is a further enlarged sectional view taken on line 99 of FIGURE 8; and

FIGURE 10 is a view similar to FIGURE 8, illustratin" the rotor indexing action.

Similar characters of reference indicate similar or iden' tical elements and portions throughout the specification and throughout the views of the drawing.

ing a fuselage 10 and wings 12, the specific design not be- 3,203,649 Patented Aug. 31, 1965 "ice ing critical. In each wing 12 are installed rotor units 14 spaced along the trailing edge 16 so that the downwash from the rotors covers substantially the entire trailing edge. It is impractical to install a rotor forward of the aileron 18 but a large tip rotor unit 20 can be used to cover as much of the aileron as possible. The larger tip rotor is easily installed in a tip compartment 22, which can be substantially full chord without cutting into the primary wing structure, the tip compartment being an addition outboard of the main structure. The rotor units 14 are dimensioned to retract into individual compartments 23 aft of the rear wing spar 24, each compartment being enclosed by wing ribs 26. Thus the forward wing structure is not weakened by the installation. Each compartment is fitted with doors 28 in the upper wing surface, mounted on hinges 3i) and operated by jacks 32. The doors can be divided into sections to accommodate the wing curvature and may be hinged and operated in any suitable arrangement for a particular installation.

It should be noted that no conventional trailing edge flap is necessary, thus ample space is available in th aft wing structure for the rotor installation.

Rotor mechanism The rotor units 14 are all similar, the tip unit 20 differing only in size, therefore only one need be illustrated and described in detail.

The rotor unit comprises a pair of rotor blades 34 attached to a hub 36 and mounted on the drive shaft 37 of a motor 33. The motor can be a small hydraulic, pneumatic or electrical type and is enclosed in a rotor head 40. Alternatively, the motor casing itself can constitute the rotor head. The power supply lines to the motor 38 are omitted for clarity, since their location and character will depend on the type of motor and available power source. On the rear of rotor head 40 are spaced lugs 42 to which a pair of rear arms 44 are attached by a hinge pin 46 having its axis perpendicular to drive shaft 37. On the forward portion of rotor head 40 are lugs 48 to which are pivotally attached a pair of forward arms 50. The other ends of arms 44 and 50 are pivotally attached to spaced brackets 52 and 54, respectively, in the lower portion of compartment 23, said arms comprising a parallel linkage by which the rotor unit can swing in a substantially vertical plane between a stored position in said compartment and an operating position above the trailing edge of wing 12. In the operating position the plane of the rotor is inclined relative to the longitudinal axis of the aircraft, so that air flow is directed slightly forwardly, for reasons hereinafter described.

In the compartment 23 is a reversible actuating motor 56 driving a longitudinally disposed jack screw 58, which is journalled between bearings 60 and 62. Riding on jack screw 53 is a traveler 64, from which an actuating link 66 extends to the forward arms 50. Rearward motion of traveler 64- thus raises the rotor unit to the operating position illustrated in FIGURE 5, while forward motion lowers the rotor unit to the stored position of FIGURE 3.,

Movement of the traveler is limited by limit switches 68 and 70, which can be mounted on bearings 60 and 62 and have plungers 72 and '74, respectively, to be contacted directly by the traveler at the limits of travel on jack screw 58 and shut off motor 56 at each end of travel. The reversible motor circuitry and limit switch arrangement is not shown, since this is conventional in various applications. Simple pilot actuated controls can be provided for operating actuating motor 56 and rotor drive motors 38.

Since the compartment 23 is necessarily narrow, it is essential that the rotor blades 34 are aligned longitudinally to retract into the compartment with striking the wing structure. This is accomplished automatically during retraction by an indexing cam 76 fixed to drive shaft 37 and an indexing dog 78 mounted on hinge pin 4-6 to move with the rear arms 44. Cam 76 is double lobed with a shape generally that of a figure 8, the lobes having V- shaped outer ends 80 and meeting at the center with opposed, inwardly V-shaped depressions 82. Dog 78 is V- shaped to fit into either depression 82, the cam 76 being disposed perpendicular to rotor blades 34, so that when the dog 78 is firmly seated into a depression, the rotor blades are longitudinally aligned with compartment 23.

The rotor blades must be aligned before the unit actually enters the compartment, so the dog must be firmly seated in the cam before the end of travel of the parallel linkage. To accommodate the last portion of travel, the dog 78 is mounted on a pin 84 being slidable in a mounting block 86 which is fixed to said hinge pin, as in FIG- URE 9, to move in unison with rear arms 4-4. Dog 78 is biased outwardly by a spring 88, the outward motion being limited by a stop pin 90 through pin 84. The stop pin 90 slides in a slot 92 inside mounting block 86 and also serves to prevent rotation of dog 78 out of alignment with the cam. In FIGURE 10, the mechanism is shown in the partially retracted position with the dog 78 initially engaging the cam 76. It will be evident that, regardless of the position of the rotor during retraction, the dog will engage the cam and bring the rotor to the correct position. The specific shapes of the cam and dog are not critical, the arrangement shown being one simple form.

Operation The rotor system is used to increase lift at low speeds and therefore shorten take-off and landing distances. For take-01f the rotor units are all extended by energizing actuating motors S6 to drive travelers 64 rearwardly. When the rotor units reach the extended position, the limit switches 70 stop the actuating motors.

Motors 38 are then operated to drive the rotors. As the aircraft moves forward the air flow over the wing is deflected down over the trailing edge by the downward airflow from the rotors, as indicated by directional ar rows in FIGURE 5. The rotor air flow thus creates aerodynamic sinks along the trailing edge in the manner of a high lift flap, the principle being well known. The aerodynamic sink effect causes the air flow to remain attached to the upper surface of the wing, even at high angles of attacks, so that breakaway and stalling are prevented.

It should be noted that the air flow from the rotors is directed somewhat forwardly due to inclination of the rotors. Forward motion of the aircraft causes the rotor air flow to be deflected back to the proper relationship with the trailing eaige. If the rotor air flow were initially straight down, the aircraft slip stream would carry the flow behind the trailing edge, so that the aerodynamic sink effect was lost. The particular angle of the rotors, their distance above the Wing and the location of their axes relative to the trailing edge will all vary according to the particular aircraft design and performance characteristics.

The lift produced by the wing, enhanced by the aerodynamic sink effect acting as a flap, together with the direct lift provided by the rotors, results in a very high total lift and greatly decreases the required take-off run. The rotors can remain in operation during the climb, enabling a heavily loaded aircraft to climb to cruising altitude in a minimum time.

To maintain the aerodynamic contours of the wing as much as possible while the rotors are in operation, the forward elements of doors 28 can be closed, as in FIG- URE 5. This arrangement has been used with aircraft landing gear doors and need not be described in detail.

In some instances where full lift increase is not necessary, the rotors can be brought up to the required rotational speed by motors 38, then allowed to autorotate due to forward motion of the aircraft in the manner of an autogiro. The aerodynamic sink effect will still be produced, although not as pronounced as with the rotors powered.

It should be understood that the rotors are merely for producing an aerodynamic effect similar to a high lift flap, with the added advantage of some direct lift from the rotors. The rotors are not intended to provide sufficient lift for vertical take-off and are, in fact, wrongly positioned with respect to the aircraft center of gravity to be used for full vertical take-off.

When cruising speed or suflicient forward speed is reach-ed, the rotors are stopped, using motors 38 to retard rotation by gradually reducing rotational speed. Suitable braking mechanism can be incorporated if motors 38 are not of a type which will provide the retarding action. As soon as the rotors are stopped the rotor units are retracted by actuating motors 56 pulling the travelers 64 forward. Near the end of retraction travel the dogs 78 engage their respective cams 76 and bring the rotor blades 34 into alignment to enter their compartments in the wing. In the fully retracted position the limit switch 68 is acuated to stop moor 56 and doors 28 arec losed, the aircraft then being in high speed configuration.

For landng, the rotor units are once more extended and motors 33 operated to rotate the rotors. During descent the rotors can be allowed to autorotate, with full power being applied just before touchdown. In this manner the aircraft can be flown at low forward speed and at a high rate of descent without danger of stalling, then the application of full rotor power increases the lift further for the flare out maneuver and actual landing.

The direct lift of the rotors some distance behind the aircraft center of gravity does not have any detrimental effect on the stability of the aircraft for several reasons. The lift derived from the rotors is not very great compared to the total lift of the wing acting about the effective center of lift. The eflicient attachment of the air flow to the upper surface of the wing caused by the rotor air flow increases the lift of the entire wing, which is effective about the designed center of lift well forward of the rotors. Also the downwash over the tail opposes any nose down pitching tendencies of the aircraft that migh occur.

The great increase in lift in low speed flight permits the use of a small wing, designed primarily for high speed flight, as opposed to a conventinal aircraft wing which must be large to provide sufficient lift at low speed. The resultant reduction in weight of basic wing structure will offset the weight of the rotor system.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification and drawings are to be considered as merely illustrative rather than limiting.

I claim:

1. In an aircraft wing, a high lift system, comprising:

at least one driven bladed rotor movably attached to said wing;

means to move said rotor between a stored position within the wing to an operating position over the wing and spaced substantially above the trailing edge portion of the wing with the rotational axis of the rotor disposed upwardly and rearwardly from the wing;

said rotor being disposed, in said operating position,

to direct air flow generally downwardly onto and over the trailing edge of the wing.

2. In an aircraft wing, a high lift system, comprising:

at least one driven bladed rotor movably attached to said wing;

means to move said rotor between a stored position within the wing to an operating position over the wing and spaced substantially above the trailing edge portion of the wing with the rotational axis of the rotor disposed upwardly and rearwardly from the wing; and

said rotor, in said operating position, being inclined relative to the plane of said wing to direct air flow forwardly and downwardly toward the trailing edge portion of the wing.

3. In an aircraft wing, a high lift system, comprising:

at least one driven rotor movably attached to said wing;

21 compartment in said wing to receive said rotor in a stored position;

actuating means to move said rotor from said compartment to an operating position spaced above the wing and substantially over the trailing edge thereof with the rotational axis of the rotor disposed upwardly and rearwardly from the wing.

4. In an aircraft wing, a high lift system, comprising: at least one driven rotor movably attached to said wing;

said rotor having a pair of diametrically opposed blades;

an elongated compartment in said wing to receive said rotor in a stored position;

actuating means to move said rotor to an operating position spaced above the wing and substantially over the trailing edge thereof;

said actuating means being operable to retract said rotor into said compartment;

and indexing means coupled to said rotor to index the blades thereof in alignment with said compartment during retraction.

5. In an aircraft wing, a high lift system, comprising:

at least one driven rotor having a hub and a pair of diametrically opposed blades;

an elongated chordwise rotor compartment in the rear portion of said Wing to receive said rotor in a stored position;

support arms pivotally attached between said hub and the rear portion of said compartment;

actuating means connected to said arms to swing said rotor upwardly and rearwardly to an operating position substantially above the wing and over the trailing edge of said wing, to direct air flow downwardly on the rear upper portion of the wing.

6. In an aircraft wing, a high lift system, comprising:

at least one driven rotor having a hub and a pair of diametrically opposed blades;

an elongated chordwise rotor compartment in the rear portion of said wing to receive said rotor in a stored position;

support arms pivotally attached between said hub and the rear portion of said compartment;

actuating means connected to said arms to swing said rotor upwardly and rearwardly to an operating position substantially above the wing and over the trailing edge of said wing, to direct air flow downwardly on the rear upper portion of the Wing; and

coacting indexing means on said rotor and said arms to inter-engage during retraction of the rotor into said compartment and index said blades into alignment with the compartment.

References Cited by the Examiner UNITED STATES PATENTS 1,866,869 7 32 Thurston 24442 1,868,832 7/32 Henter 244 1,927,537 9/33 Zaparka 244-10 2,511,025 6/ Tucker a- 244-7 2,928,626 3/60 T ino 244-10 2,973,167 2/ 61 Lake 244--42 3,121,544 2/ 64 Alvarez-Calderon.

FOREIGN PATENTS 678,398 7/40 Germany. 885,666 12/61 Great Britain.

MILTON BUCHLER, Primary Examiner. 

1. IN AN AIRCRAFT WING, A HIGH LIFT SYSTEM, COMPRISING: AT LEAST ONE DRIVEN BLADED ROTOR MOVABLY ATTACHED TO SAID WING; MEANS TO MOVE SAID ROTOR BETWEEN A STORED POSITION WITHIN THE WING TO AN OPERATING POSITION OVER THE WING AND SPACED SUBSTANTIALLY ABOVE THE TRAILING EDGE PORTION OF THE WING WITH THE ROTATIONAL AXIS OF THE ROTOR DISPOSED UPWARDLY AND REARWARDLY FROM THE WING; 